In situ phytomanagement with Brassica napus and bio-stabilised municipal solid wastes is a suitable strategy for redevelopment of vacant urban land

Abstract The decline of industrial manufacturing left large areas of vacant land in the peri-urban belts of many European cities, becoming an economic, social and environmental concern. In the meantime, available fertile soils are being over-used to produce energy crops, and municipal organic wastes are accumulating in landfills, actions that hamper the development of wealth-creating and sustainable societies. Phytomanagement has emerged as a valuable in-situ strategy for the management of peri-urban vacant spaces, able to restore their fundamental ecosystem services. The field experiment described here was undertaken to study the potential of bio-stabilised material (BSM) obtained from commingled municipal solid wastes, both for Brassica napus (rapeseed) crop production and to improve the health/functioning of peri-urban vacant soil as a first step toward urban greening. Three months before sowing, soils were amended with 0, 50 and 100 t FW BSM ha–1. Data were gathered on the physiology and growth of B. napus at the BBCH-16-17 (57 days) and BBCH-89 (260 days) phenological stages. The activity, biomass, and functional diversity of soil microbial communities were measured concomitantly. Overall, the results showed that the BSM-amended soils became more productive and functional than the unamended soils. At the plant level, the leaf area of B. napus plants was significantly increased at the BBCH-16-17 stage, which later, at BBCH-89 stage, translated to a higher yield. At the soil level, mainly microbial activities related to C and N turnover increased after BSM amendment. This was key in satisfying the oilseed nutritional requirements under our experimental conditions. This innovative study advocates for a circular economy and shows that the combination of BSM amendment and B. napus can be efficacious for the redevelopment of peri-urban vacant soils.